The introduction of multifunctionalities for tumour targeting is becoming a popular strategy toward the development of new therapeutic agents. In particular, the multifaceted potential of ruthenium(II)-arene complexes show great promise as chemotherapeutics. An ever-increasing number of papers dealing with the integration of ruthenium complexes with biologically active molecules to derive bioorganometallic molecules of chemotherapeutic significance have been published in recent years. This perspective review presents a short overview of multifunctional ruthenium-based drugs, especially those containing arene ruthenium complexes, with the emphasis on the combination of photosensitizers with ruthenium complexes for the preparation of novel multifunctional photodynamic therapy agents.

Chelating neutral (N,O) and cationic (N,N) first- and second-generation ruthenium(II) arene metallodendrimers based on poly(propyleneimine) dendrimer scaffolds were obtained from dinuclear arene ruthenium precursors by reactions with salicylaldimine and iminopyridyl dendritic ligands, respectively. The N,N cationic complexes were isolated as hexafluorophosphate salts and were characterised by NMR and IR spectroscopy, and MALDI-TOF mass spectrometry. Related mononuclear complexes were obtained in a similar manner and their molecular structures have been determined by X-ray diffraction analysis. The cytotoxicities of the mono- and multinuclear complexes were established using A2780 and A2780cisR human ovarian carcinoma cancer cell lines.

A series of aryl-functionalized and ferrocenyl monothiosemicarbazone compounds (L1–L4) were synthesized in moderate yields via a general Schiff-base condensation reaction. The thiosemicarbazone (TSC) ligands were reacted with the ruthenium dimer [Ru(Ar)(μ-Cl)Cl]₂ (Ar = benzene; p-cymene) to yield a series of cationic mononuclear ruthenium(II)–arene thiosemicarbazone complexes of the general type [Ru(Cl)(TSC)(Ar)]Cl (1–8). The thiosemicarbazone ligands act as bidentate chelating ligands that coordinate to the ruthenium(II) ion via the imine nitrogen and the thione sulfur atoms. The thiosemicarbazone ligands, as well as their metal complexes, were characterized by NMR, IR spectroscopy and ESI⁺-mass spectrometry. The molecular structure of the mononuclear ruthenium(II)–arene thiosemicarbazone complex (6) was determined by single-crystal X-ray diffraction analysis. The ruthenium(II)–arene thiosemicarbazone complexes were further evaluated for their in vitro antiparasitic activities against the Plasmodium falciparum chloroquine-sensitive (NF54) and chloroquine-resistant (Dd2) strains, as well as the G3 strain of Trichomonas vaginalis.